=over

=item msgctl ID,CMD,ARG
X<msgctl>

Calls the System V IPC function L<msgctl(2)>.  You'll probably have to say

    use IPC::SysV;

first to get the correct constant definitions.  If CMD is C<IPC_STAT>,
then ARG must be a variable that will hold the returned C<msqid_ds>
structure.  Returns like L<C<ioctl>|/ioctl FILEHANDLE,FUNCTION,SCALAR>:
the undefined value for error, C<"0 but true"> for zero, or the actual
return value otherwise.  See also L<perlipc/"SysV IPC"> and the
documentation for L<C<IPC::SysV>|IPC::SysV> and
L<C<IPC::Semaphore>|IPC::Semaphore>.

Portability issues: L<perlport/msgctl>.

=back